1. Field of the Invention
The present invention relates generally to an improved, low cost magnetic drain bolt, and more particularly to a drain bolt having a magnet secured at an end thereof for attracting metallic particles in an oil pan of an automobile to prevent the metallic particles from interfering with sensors within the engine.
2. Description of the Prior Art
In an automobile engine, oil circulates between the engine, a reservoir and an oil pan. Oil is used to lubricate the engine to diminish the friction between the piston and the cylinder. This friction can cause small metal shavings and other debris to circulate in the oil. The oil is also used to convey heat and debris from the engine. An oil filter is typically used in the circulation path of the oil to filter out debris and particles in the oil. However, small metal shavings in the oil are not always filtered and cannot only cause excessive wear on the engine, but can also disrupt sensors that are now found in the engines of many vehicles, such as a crank shaft position sensor. These sensors can give false readings if too many metal shavings and particles come into contact with the sensor. It is therefore desirable to provide a method of removing such particles from the oil to prevent excessive wear on the engine and to enable the sensors in the engine to work properly.
One solution is to provide a magnetic drain plug positioned in the plug hole of an oil pan. Different types of magnetic drain plugs exist, however, they are either not strong enough to attract the metal shavings and particles in the oil or they are too costly to manufacture.
Conventional magnetic drain bolts typically have a magnet inserted into a recess on the bolt. Such conventional drain bolts require the magnet to be attached to the bolt body using an adhesive and/or press fitting the magnet within the recess. Adhesives do not always work properly and can cause the magnet to dislodge from the drain bolt due to exposure to hot oil within the oil pan or just dropping the drain bolt on the ground. Adhesively secured magnets can also fall off when handling the bolts during shipping and assembly. The press fitting techniques disclosed in the prior art would require placing excessive forces onto the magnet that could damage low cost magnets such as sintered ferrite slugs. Other magnetic type of drain bolts disclose the use of different types of magnets, such as synthetic resin, rare earth or ceramic type magnets. These types of magnets are more expensive than sintered ferrite magnetic materials and further increase the cost of the magnetic drain bolt.
Conventional magnetic drain bolts can initially have a strong magnetic force when first magnetized. After the magnetic drain bolts come into contact with other magnetic drain bolts and/or magnets, the magnetic force of the drain bolt is "knocked down" and becomes weaker. Such conventional magnetic drain bolts are typically knocked down during the shipping process and can degrade from 40-60 percent, thereby ultimately providing a much weaker drain bolt than initially created and therefore not providing the magnetic force necessary to attract metallic particles and shavings in an oil pan of an engine.
These and other types of magnetic drain bolts disclosed in the prior art do not offer the flexibility, robust structure and inventive features of the magnetic drain bolt described herein. As will be described in greater detail hereinafter, the magnetic drain bolt of the present invention differs from those previously proposed.
It therefore would be desirable to provide a low cost magnetic drain bolt that does not use adhesive and does not assert a significant force on the magnet which could tend to damage the magnet. It is further desirable to provide a magnetic drain bolt that is similar in size and length to a non-magnetic drain bolt, easy to manufacture, less expensive to manufacture, degrades less than conventional magnetic drain bolts after being knocked down and still provides a strong magnetic attraction in order to attract metallic shavings and particles in an oil pan of an engine.